Different modalities are used in medical imaging. The important modalities are, for instance, ultrasound, computed tomography (CT), or magnetic resonance tomography (MRT). Depending on the clinical application and situation, the best suited imaging modality may be used.
With the acquisition of image data, the imaging modalities use different methods. During the acquisition, a measured data space may be filled with data that is required to calculate an image, and the image is calculated thereupon.
With MRT, a Fourier space, which may also be referred to as k-space or spatial frequency space, may be filled with data and an image is produced therefrom by Fourier transformation. The size of the measured data space, in other words the number of data points to be acquired, may be determined by parameters such as resolution, matrix size, slice thickness, and number of slices. The measurement time required for the acquisition may be proportional to the size of the measured data space.
It is advantageous for many applications to keep the measurement time as minimal as possible, in order, for instance, to keep the dosage low or to be able to display rapidly occurring processes.